Calculate the amount of 0.100M sodium acetate (ml) that needs to be added to 100.0 ml of 0.530 M acetic acid

Question

to make a solution of pH= 3.00

Answer 1

a pH = 3.00, ... has a H+ = 1e-3 Molar

HC2H3O2 --> H+  & C2H3O2-

Ka = [ H+] [C2H3O2-] / [HC2H3O2]

1.8e-5 = [ 1e-3] [C2H3O2-] / [HC2H3O2]

1.8e-2 = [C2H3O2-] / [HC2H3O2]

we need this ratio of molarities..[C2H3O2-] / [HC2H3O2]  = 1.8e-2

which is identical to the ratio of (molesC2H3O2-) / (moles HC2H3O2)

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fso, ind the moles of acetic acid:

0.100Litres @ 0.530 mol/litre = 0.053 moles of acid,... so

if (moles C2H3O2-) / (moles HC2H3O2) = 1.8 e-2  .... then

(moles C2H3O2-) / (0.053moles) = 1.8 e-2 , .... then

(moles C2H3O2-)  = 1.8 e-2  (0.053moles)

we need to add or have C2H3O2-  = 9.54e-4 moles

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to get 9.54e-4 moles of  acetate, how many mls of 0.100M sodium acetate needs to be added:

9.54e-4 moles @ 0.100 mol / litre = 9.54e-3 litres

your answer is 9.54 millilitres of 0.100 M sodium acetate needs to be added